The present invention relates to methods and apparatus for separating the glass panel from a cathode ray tube, and more particularly, to methods and apparatus using a vibratory conveyer to separate the glass panel from a cathode ray tube.
A typical cathode ray tube (CRT) is made largely of glass and may include a funnel or bell portion and a panel portion bonded together by a ceramic frit. The funnel portion may include such components as an electron gun and a shadow mask. Cathode ray tubes also include an implosion band—a metal band strapped around the panel portion of the cathode ray tube approximately one-quarter to three-quarters inches from the ceramic frit line.
A typical cathode ray tube is made up of two types of glass, both of which are impregnated with a metal in order to reduce the emission of x-rays and other radiation from the electron gun, and with respect to the panel, to improve clarity. The panel glass makes up approximately 70% of the weight of a cathode ray tube and may contain approximately 0.05-4.0% lead in the form of lead oxide (PbO). In later model CRTs, panel glass contained barium oxide instead of lead oxide. In contrast, the funnel glass, which makes up approximately 30% of the weight of the CRT, may contain as much as 18-22% lead. The bonding ceramic frit is a lead oxide paste that may contain as much as 70-85% lead.
At one time, such cathode ray tubes were used extensively in televisions, computer monitors and other video monitors, as well as for oscilloscopes and other types of electronic displays incorporated in electronic equipment. However, cathode ray tubes are no longer in demand for such products, having been replaced by screens incorporating more modern display technologies such as liquid crystal display (LCD), plasma display, and organic light emitting diode (OLED). Since the manufacture of cathode ray tubes is now all but nonexistent, there is no demand for discarded cathode ray tubes to be recycled and their components to be reused to make new cathode ray tubes. It is now necessary to dispose of the various components of a CRT in compliance with regulations regarding lead-containing waste, as well as general recycling of glass with lead content.
Typically, lead content in glass products for recycling may not exceed 0.05%. Consequently, panel glass of a CRT may be recycled, but not the frit or the funnel glass. In order to recycle CRT panel glass, it is necessary to separate the low-lead content panel glass from the high-lead content funnel glass and frit portion of a CRT. Current technologies may utilize a mechanical saw to cut the panel glass from the funnel glass and frit of the cathode ray tube. Such mechanical saws may include a laser or a diamond-coated metal blade, water jet, or hot water.
A disadvantage with using such mechanical saws is that the sawing process is time consuming and therefore expensive. Typically, use of such saws to separate panel glass from the frit and funnel glass of a CRT operates at a speed of from one to four tubes per minute. In addition, if the CRT is received with a broken funnel, it may be difficult to align the tube in the saw to make an accurate cut.
Other types of devices have been utilized to separate the panel from the frit and funnel of a cathode ray tube. For example, vibratory screeners have been employed in which a processor separates the glass from a completely broken up cathode ray tube by lead concentration using x-rays. However, while production from such a process may be higher in terms of pounds per hour, the purity of the recovered panel may be compromised, and conversely, a significant amount of clean panel may be discarded along with broken-up funnel and frit material.
Accordingly, there is a need for a process and apparatus that separates the panels of a cathode ray tube from the frit and funnel components that is accurate, and provides a relatively high production rate and low cost.